This invention relates to an apparatus used for guiding an instrument in a surgical operation such as a brain surgical operation.
For example, in a surgical operation for removing a hematoma from a brain, various surgical instruments such as an endoscope and a suction tube for sucking blood are inserted into the brain through a hole formed in the skull of a patient. A typical guiding apparatus for guiding the endoscope, the suction tube, etc. generally comprises a sheath for allowing passage of those surgical instruments, and a mandrel. The mandrel is used when the sheath is inserted into the brain. A distal end portion of the mandrel is rounded and projected from a distal end of the sheath so that it will not damage the brain when the sheath is inserted into the brain. After the distal end portion-of the mandrel reaches the hematoma, the mandrel is withdrawn and the endoscope and the suction tube are inserted into the sheath.
With this conventional construction, an assistant to the surgeon must keep holding the sheath while maintaining a proper depth and angle of insertion into the brain (body) during the time the surgeon performs an operation using the endoscope and the suction tube. This imposes a great burden on the assistant.
Japanese Unexamined Patent Publication (Kokai) No. Hei 9-154803 discloses a guiding apparatus including a transparent sheath but it does not disclose any means for restricting the depth of insertion of the sheath.
It is an object of the present invention to provide a guiding apparatus capable of properly restricting the depth of insertion of a sheath into the body of a patient.
In order to achieve the above object, a stopper for limiting the depth of insertion of a sheath of a guiding apparatus into the body of a patient is disposed on an outer periphery of the sheath. This stopper is capable of displacing the sheath in an axial direction. In the case where the guiding apparatus is used for a brain operation, the stopper is brought into abutment with the skull of the patient.
Preferably, the stopper is slidably supported by the sheath and a lock mechanism is disposed on the stopper. This lock mechanism releasably locks the stopper to the sheath.
More preferably, a first hole and a second hole are formed in the stopper. The first hole is in the form of a through-hole and a second hole has a closed end and an open end. The first and second holes are generally in orthogonal relation with their axes offset and they are in communication with each other at their intermediate sections. The sheath is slidably inserted into the first hole and a lock member is slidably inserted into the second hole. A recess is formed in that area of the lock member which faces the first hole. The sheath is partly received in the recess. One end portion of the lock member projects from the open end of the second hole and serves as a control portion. Biasing means is received in the closed end of the second hole. The biasing means biases the lock member so as to urge a surface of the recess against an outer peripheral surface of the sheath so that the sheath is locked. The urged state of the lock member against the sheath is released by a force applied to the control portion against the effect of the biasing means. Consequently, the locked state of the sheath is released, too.